In a method and a device to generate a print image on a carrier material, ink-attracting and ink-repelling regions corresponding to the structure of the print image to be printed are generated on the surface of the print substrate, whereby ink is applied to the surface of the print substrate that adheres to the ink-attracting regions and is not accepted by the ink-repelling regions, and in that the ink distributed on the surface is printed on the carrier material.
In the prior art, offset printing methods operating in waterless are known whose unprinted regions are oil-repelling, and therefore accept no printing ink. In contrast, the printed regions are oil-attracting and accept the oil-based printing ink. Ink-attracting and ink-repelling regions are distributed on the printing plate corresponding to the structure of the printing image to be printed. The printing plate can be used for a plurality of transfer printing events. A new plate with ink-attracting and ink-repelling regions must be generated for each printing image.
A method is known from U.S. Pat. No. 5,379,698 that is called a direct imaging method, in which a printing pattern is created on a multi-layer, silicon-coated film in the print device via selective burning away of the silicon cover layer. The silicon-free locations are the ink-attracting regions that accept printing ink during the print event. It requires a new film for each new printing image.
In the standard offset method, operating with water, hydrophobic and hydrophilic regions are generated on the surface of the print substrate, corresponding to the structure of the printing image to be printed. Before the application of the ink, a thin moisture film is applied to the print substrate using inking rollers or spray devices that moisten the hydrophilic regions of the print substrate. The ink roller subsequently transfers ink onto the surface of the print substrate that, however, exclusively moistens the regions not covered with the moisture film. The ink is finally transferred onto the carrier material after the inking.
In known offset printing methods, multi-layer process-less thermoprinting plates can be used as a print substrate (compare, for example, WO/16988). Corresponding to the structures of the printing image to be printed on the surface of the print substrate, a hydrophobic layer is removed via partial burning, and a hydrophilic layer is uncovered. The hydrophilic layer can be moistened with an ink-repelling dampening agent. The hydrophobic regions are ink-accepting and can accept printing ink during the printing event. A new printing plate must be used to create a new printing image.
Furthermore, a method is known from U.S. Pat. No. 6,016,750 in which, from a film, an ink-attracting substance is deposited by means of a thermo-transfer method, transferred to the hydrophilic surface of the print substrate, and consolidated in a fixing process. In the printing process, the free hydrophilic regions are moistened with ink-repelling dampening agent. The ink is subsequently applied to the surface of the print substrate that, however, only accepts at the regions provided with the ink-attracting substance. The inked printing image is then transferred to the carrier material. A new film with the ink-attracting substance is necessary for the creation of a new printing image.
The aforementioned methods have the problem that the print substrate must be remade before the creation of a new printing image or the surface of the print substrate can only be cleaned outside of the printing device or additional ink-attracting substances are required.
A device and a method to illustrate a printing form for wet-offset printing is known from DE-A-199 11 906. In a first variation, the surface of the print substrate is completely moistened with an ink-repelling dampening agent. Image regions are dried by means of radiation that are then ink-accepting. In a second variation, the surface of the print substrate is completely covered with ink. With the aid of radiation, this ink is dried at image locations. At non-image locations, the ink is removed via an ink-repelling dampening agent.